The plague of the zombies (1966)

Sir James Forbes arrives in a remote Cornish village to identify a mysterious plague afflicting the population. Local squire Charles, a disciple of Haitian witchcraft, is using the voodoo magic to resurrect the dead to work in his decrepit and unsafe tin mines that are shunned by the local population. But his magic relies on human sacrifice and he unleashes his army of the undead on the unsuspecting village with horrific consequences.